To make the cauliflower cheese, preheat the oven to 170c/325f/gas4. Prepare a pan of boiling water with a steaming basket. Place the cut florets and prepare the leaves a place them into the steam basket. Lower the basket into the pan put the lid on and steam for 5-6 minutes until just tender. Remove and set aside.
To make the sauce; melt the butter in a medium saucepan over a low heat, add the flour and stir well to combine to a smooth sandy paste. Allow to cook for 2-3 minutes. Gradually add the warm milk, stirring well between additions. Bring to the simmer, use a whisk to beat out any lumps. When gently simmered; add 100gm of the grated cheese, mustard and salt & pepper to taste.
Gently stir in the prep-cooked cauliflower. Place the mixture into a baking dish.
Preheat the oven to 170c. Prepare the breadcrumbs by placing them in a food processor and adding the parsley. Blend until smooth green tinged breadcrumbs are formed.
Sprinkle the remaining cheese on top of the cauliflower, followed by a generous handful of the breadcrumbs. Bake for 15-20 minutes until the cauliflower is golden and crispy on top. Serve swiftly.
To add another layer of sweet nutty vegetables you can roast the cauliflower in some olive oil instead of steaming it.
The layer of breadcrumbs on the top of the cauliflower gives a great crunchy texture. You can make these ahead of time with some leftover bread, that can then be stored in the freezer.